speckle-impl-connectors-overview

name	speckle-impl-connectors-overview
description	Use when understanding Speckle connector architecture, planning cross-tool data exchange, or debugging conversion pipelines. Prevents misunderstanding of the ToSpeckle/ToHost conversion flow, incorrect applicationId assumptions, and missing proxy architecture patterns. Covers DUI3 shared UI, conversion pipeline (ToSpeckle/ToHost), supported connectors matrix, connector SDK, proxy architecture, data schema for connectors, applicationId, and units handling. Keywords: speckle connector, conversion, ToSpeckle, ToHost, DUI3, applicationId, proxy, data schema, connector matrix, Archicad, Navisworks, Dynamo, which connector, supported software.
license	MIT
compatibility	Designed for Claude Code. Requires Speckle Server 2.x/3.x, Speckle Connectors (latest).
metadata	{"author":"OpenAEC-Foundation","version":"1.0"}

speckle-impl-connectors-overview

Quick Reference

Connector Architecture

Component	Role	Location
DUI3 (Desktop UI 3)	Shared UI across all connectors	Embedded in host application
Conversion Pipeline	ToSpeckle / ToHost object transformation	Connector SDK
Transport Layer	Serialization and server communication	Speckle SDK
Proxy System	Shared resource references (materials, levels, groups)	Root Collection
Speckle Desktop Service	Authentication token management	System service

Supported Connectors Matrix

Connector	Versions	OS	Publish	Load	Native on Load	Schema Type
Revit	2022-2026	Win	Yes	Yes	Direct Shapes	RevitObject
Rhino	7, 8	Win	Yes	Yes	Geometry	Geometry/Instance
Grasshopper	(bundled with Rhino)	Win	Yes	Yes	Geometry	Geometry/Block/Data
Blender	4.2-5.0	Win/Mac	Yes	Yes	Mesh/Curves	Geometry
AutoCAD	2022-2026	Win	Yes	Yes	Geometry	Geometry/Instance
Civil 3D	2022-2026	Win	Yes	Yes	Geometry	Civil3dObject
Tekla	2023-2025	Win	Publish only	No	N/A	TeklaObject
Archicad	27-29	Win	Yes	Yes	GDL Objects	ArchicadObject
SketchUp	2021-2026	Win/Mac	Yes	Yes	Components	Geometry
Power BI	N/A	Win	No	Read only	Tabular + 3D	N/A

Critical Warnings

NEVER assume native element recreation on load -- Revit ALWAYS creates Direct Shapes, Archicad ALWAYS creates GDL Objects. There is NO native wall/door/floor reconstruction from Speckle data.

NEVER assume all connectors support bidirectional data flow -- Tekla is publish-only and Power BI is read-only. ALWAYS verify publish/load capability before designing a workflow.

NEVER reference objects by id in proxy relationships -- id is a content-based hash that changes when data updates. ALWAYS use applicationId for cross-version tracking and proxy references.

NEVER expect custom properties to round-trip through all connectors -- Revit, Blender, and Archicad do NOT load custom properties back onto received objects. ALWAYS verify property behavior for your specific connector pair.

NEVER expect texture support -- Speckle does NOT transfer textures across any connector. Only material properties (color, opacity, metallic, roughness) survive the pipeline.

NEVER publish solids from AutoCAD/Civil 3D expecting solid geometry downstream -- solids are ALWAYS converted to Mesh geometry irreversibly.

---

Conversion Pipeline

ToSpeckle Flow (Publish)

Host Application Object
        |
        v
[1. Selection] --> Manual / View-based / Category-based / All Visible
        |
        v
[2. Conversion] --> Native Object --> Speckle Base Object
        |               |
        |               +--> displayValue: [Mesh, Line, Point]  (interoperable geometry)
        |               +--> properties: { key: value }          (semantic metadata)
        |               +--> applicationId: "native-id"          (stable identifier)
        |               +--> units: "mm" | "m" | "ft" | "in"    (measurement system)
        |
        v
[3. Proxy Extraction] --> Materials, Levels, Groups, Definitions, Colors
        |                   (stored at Root Collection, reference by applicationId)
        |
        v
[4. Transport] --> Serialize + Send to Speckle Server

ToHost Flow (Load/Receive)

Speckle Server
        |
        v
[1. Fetch] --> Download objects from server
        |
        v
[2. Conversion] --> Speckle Object --> Host Application Object
        |               |
        |               +--> Attempt native reconstruction (connector-specific)
        |               +--> Fall back to generic representation if native fails
        |
        v
[3. Proxy Resolution] --> Apply materials, assign levels, restore groups
        |
        v
[4. Placement] --> Insert into host application scene/document

Asymmetric Fidelity Rule

Publishing ALWAYS preserves MORE information than loading. A Revit wall published to Speckle retains all parameters, material quantities, and type information. When loaded into Rhino, it becomes geometry with properties as user strings. When loaded back into Revit, it becomes a Direct Shape, NOT a native wall. This asymmetry is fundamental and by design.

---

Object Types

Three Object Categories

Category	Description	Primary Use
Geometry Objects	Pure primitives (Point, Line, Mesh, Brep, Arc, Polyline)	CAD workflows (Rhino, AutoCAD)
DataObject	Semantic elements with properties + displayValue	BIM workflows (Revit, Archicad, Tekla, Civil 3D)
Instance Objects	References to Definition proxies via definitionId + 4x4 transform	Blocks, components, repeated geometry

DataObject Extensions by Connector

Connector	Type	Extra Fields
Revit	RevitObject	type, family, category, level, location, referencePointTransform, views
Archicad	ArchicadObject	type, level, location
Civil 3D	Civil3dObject	type, baseCurves
Tekla	TeklaObject	type, properties.Report

displayValue Convention

EVERY connector places interoperable geometry in the displayValue array using minimum viable primitives: Mesh, Line, Point. This ensures ANY receiver can render the geometry even without native reconstruction. Brep data MAY be preserved for connectors that support it (Rhino), but Mesh is the universal fallback.

---

Proxy Architecture

Five Proxy Types

Proxy	Purpose	Used By
RenderMaterial	Color (RGB), opacity, metallic, roughness	All connectors
Level	Elevation data and level name	BIM connectors (Revit, Archicad)
Group	Functional grouping (objects can belong to multiple groups)	Revit, Rhino, AutoCAD, Civil 3D
Definition	Block/component geometry stored once, reused by Instances	Rhino, AutoCAD, Civil 3D
Color	Simple hex color (#RRGGBB)	CAD connectors (AutoCAD, Civil 3D)

Proxy Structure

Every proxy follows this structure:

{
  "speckle_type": "Objects.Data.RenderMaterialProxy",
  "applicationId": "mat-001",
  "name": "Concrete Gray",
  "value": { "diffuse": 12632256, "opacity": 1.0, "metalness": 0.0, "roughness": 0.8 },
  "objects": ["elem-101", "elem-102", "elem-205"]
}

Proxy Invariants

• Proxies ALWAYS reference objects by applicationId, NEVER by id
• Proxies NEVER reference other proxies -- no circular references permitted
• Proxies are ALWAYS stored at the Root Collection level
• A single proxy can reference hundreds of objects

---

Identity System

Field	Purpose	Stability
id	Content-based hash (SHA256 of object data)	Changes when ANY data changes
applicationId	Source application identifier (Revit ElementId, Rhino GUID, AutoCAD Handle)	Stable across publish/load cycles
speckle_type	Type discriminator (e.g., "Objects.Data.DataObject:Objects.Data.RevitObject")	Fixed per object type

applicationId Stability Across Cycles

When a Revit wall is modified and republished:

• applicationId remains the same (Revit ElementId persists)
• id changes (content hash reflects updated data)
• Proxies continue referencing via the stable applicationId

This enables change tracking, version comparison, and proxy resolution across multiple publish cycles.

---

Units Handling

Every object carries a units field. Supported values: "m", "mm", "cm", "ft", "in", "yd".

Unit conversion happens automatically during the conversion pipeline. The connector reads the host application's document units and writes them into each object. On the receiving side, the connector converts incoming units to match the target document.

---

Collection Hierarchies by Connector

Each connector preserves its native organizational structure:

Connector	Hierarchy
Revit	File > Level > Category > Type > RevitObject
Rhino	File > Layer > Sublayer > Objects
AutoCAD	File > Layer > Objects
Civil 3D	File > Layer > Objects
Archicad	File > Floor > Type > ArchicadObject
Tekla	File > Type > TeklaObject
Blender	File > Collection > Objects
SketchUp	File > Layer > Components

---

Connector-Specific Load Behavior

Connector	What Objects Become on Load
Revit	Direct Shapes (generic models). NEVER native elements.
Rhino	Geometry, text, or blocks. Materials and user strings preserved.
Grasshopper	Geometry Objects, Block Objects, or Data Objects. NEVER native BIM elements.
Blender	Mesh/Curves. Block loading: collection instances (default) or linked duplicates.
AutoCAD	Geometry, text, or blocks. Flattened layer structure. Selection Sets created.
Civil 3D	Same as AutoCAD (inherits AutoCAD behavior).
Archicad	GDL Objects (generic models). Organized in embedded library folders.
SketchUp	Components with matching layer structure. Properties as user attributes.
Tekla	N/A -- publish-only, no load capability.
Power BI	Tabular data + 3D visualization. Read-only.

---

Data Federation

Federated Views

Multiple models from different tools assemble into a single federated view. An architect's Revit model, a structural engineer's Tekla model, and a landscape designer's Rhino model can all coexist in one Speckle project.

Geometry Baking for Interoperability

All connectors bake geometry into minimum viable interoperable primitives in displayValue. This guarantees that ANY receiver can display ANY source geometry regardless of native format support.

Common Cross-Tool Workflows

1. Revit to Grasshopper to Revit: Publish from Revit, load in Grasshopper for parametric analysis, publish back. On return to Revit, objects become Direct Shapes.
2. Multi-discipline coordination: Multiple teams publish to the same project. Federated view shows all models together.
3. Design option comparison: Publish versions from different tools, compare in viewer.

---

DUI3 Shared UI

DUI3 (Desktop User Interface 3) provides a consistent interface across all connectors:

• Project and model selection
• Publish and load controls
• Version history navigation
• Account management
• Communicates with Speckle Desktop Service for authentication

EVERY connector uses DUI3. The UI behavior is identical regardless of host application.

---

Reference Links

• references/methods.md -- Connector API methods, conversion signatures, proxy structures
• references/examples.md -- Cross-tool workflow examples with data flow diagrams
• references/anti-patterns.md -- Common mistakes with connector workflows

Official Sources

• https://docs.speckle.systems/developers/data-schema/overview.md
• https://docs.speckle.systems/developers/data-schema/concepts.md
• https://docs.speckle.systems/developers/data-schema/proxy-schema.md
• https://docs.speckle.systems/developers/data-schema/connector-index.md
• https://docs.speckle.systems/connectors/revit/revit.md
• https://docs.speckle.systems/connectors/rhino/rhino.md
• https://docs.speckle.systems/connectors/grasshopper/grasshopper.md
• https://docs.speckle.systems/connectors/blender.md
• https://docs.speckle.systems/connectors/autocad.md
• https://docs.speckle.systems/connectors/civil3d.md
• https://docs.speckle.systems/connectors/tekla.md
• https://docs.speckle.systems/connectors/archicad.md
• https://docs.speckle.systems/connectors/sketchup.md
• https://docs.speckle.systems/connectors/power-bi/power-bi.md